Machines such as integrated tool carriers, skid steer loaders, agricultural tractors, excavators, and other machines have a variety of tools that may be attachable to the machine to perform different tasks. These machines and tools may be controlled through a control system having one or more operator input devices such as, for example, levers, foot pedals, joysticks, and other devices known in the art. Each tool may require different control parameters for the operator input devices to accomplish the different tasks. For example, an operator of a tool carrier having a fork attachment may require precise control over tool movement speed or machine travel speed during a stacking operation, while such precise control may not be required for the same tool carrier having a bucket attachment for performing earth moving operations. In addition, a machine with no tool attached may require precise travel speed control at low travel speeds to facilitate a tool attachment procedure, but less precise travel speed control at higher speeds when the tool is attached and the machine is traveling between jobsites or tool storage locations. These machines may be configured to automatically change control parameters based on an identification of an attached tool.
One method to identify a tool is by means of a Radio Frequency Identification (RFID) system. RFID systems enable data to be transmitted by a identification device, called a tag, which is read by an RFID receiver and processed according to the needs of a particular application. The data transmitted by the tag may provide identification or location information about the tag. Typically, identification is achieved by bringing an RFID transmitter within range of an RFID receiver and reading the information contained on the tag. A tool having an RFID tag attached may be similarly identified when the tool comes within a range of the RFID receiver. However, when multiple tools having RFID tags are within range of the RFID receiver, identification of a particular tool becomes more difficult.
It is known to identify and track a particular RFID tag by comparing signals received from the RFID tag at different times to determine a relative change in distance between the RFID tag and the RFID receiver. One such example is U.S. Patent Publication Number 2005/0052287 (the '287 publication) to Whitesmith et al., which was published on Mar. 10, 2005. The '287 publication discloses a system and method having RFID tags for emitting short bursts of RF energy at periodic intervals. The system also has RFID detectors for receiving signals from the particular RFID tag and control means for comparing the signals received from the particular RFID tag at different times to determine a relative change in distance between the RFID tag and the RFID receiver. In the '287 publication, the RFID detector ascertains certain parameters of the RF signal received from the particular RFID tag including the period of time between pulses of the signal, the length of the pulses, or the amplitude of the pulses. Variations in these parameters are the result of changes in the relative positions of the receiving unit and the particular RFID tag. The change in relative position is indicative of a change in location of either the RFID tag, the RFID detector, or both.
Although the system of the '287 publication may enable the detector to track by sensing a relative change in distance between the particular RFID tag and the RFID detector, the system does not provide a way to identify and track the RFID tag based on the variance in the received parameters. Thus, when multiple tags are in use in the system of the '287 publication, the system cannot identify and track a particular RFID tag based on the motion of the tag.
The disclosed system is directed to overcoming one or more of the problems set forth above.